I have designed a board with 3254A device. When I connect the USB cable from the PC to run the DEMO APP given by ST, the total WINDOWS hangs. I have designed as per the DK3200 demo kit schematics, means for USB I have provided a 7.5K pull-up on USD_D- line and removed the additional LM339 circuitry.

Can any one help me out in debugging why Windows OS hangs immediately upon connecting the 3254A hardware to the PC.